Centrifugal classifier



J. M. DAVIS CENTRIFUGAL CLASSIFIER June 23, 1953 Filed Sept. 22, 1949' FIG. 2

FIG. 1

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. INVENTOR JQHN MARSHALL DAVIS syzlwwui;

ATTORNEY Patented June 23, 1953 UNITED STATES PATENT OFFICE CENTRIFUGAL CLASSIFIER John Marshall Davis, Chamblee, Ga.

Application September 22, 1949, Serial No. 117,120

This invention relates to a centrifugal classifier, and more particularly to a classification, desliming and dewatering device to separate materials, such as natural sands, crushed or ground metallic or non-metallic ores, as to particle size or gravity differentials, using the principles of centrifugal force, free settling and a controlled rising current within the apparatus.

An object of my invention is to provide a centrifugal classifier into which material is intro duced tangentially and removed centrally or exially of the apparatus.

Another object of my invention is to provide an open top centrifugal classifier in which the angular velocity is readily controlled.

Another object of my invention is to provide a centrifugal classifier in which the zone of overhow is adjustable.

Another object of my invention is to provide a centrifugal classifier in which the particle size of separation is fully controlled.

Another object of my invention is to provide a centrifugal separator which is simple in design, inexpensive to manufacture, rugged in construction and efiicient in operation.

Other and further objects and advantages of my invention will be apparent from the following description taken in connection with the accompanying drawing in which like characters of reference designate corresponding parts throughout the several views, and wherein:

Fig. 1 is a side elevation, with parts broken away, showing a centrifugal classifier embodyihg my invention.

Fig. 2 is a top plan view of the apparatus shown in Fig. l.

Fig. 3 is a cross-sectional view taken along the line 3--3 in Fig. 1. V

Fig. 4 is a cross-sectional view taken along the line ii in Fig. 2.

In the embodiment chosen for illustration, an open top tank I!) is provided with a cylindrical upper side wall H, and a cone shaped lower wall i2 which terminates in a discharge opening E3. The conical wall l2 makes an angle of approximately 60 with the horizontal. Material is introduced into the tank tangentially about the cylindrical upper side wall ll through the conduit M.

Heavy classified material is discharged from the tank H] through the lower central opening i3, and lighter classified material is discharged from the tank It through an upper central discharge opening l5 comprising a funnel shaped end on the discharge tube I6. The discharge 5 Claims. (01. 209-211) tube l6 extends downwardly about the central vertical axis of the tank Hi to a point near the lower discharge opening I3 and then extends outwardly from the tank. It will be noted that both the discharge opening for the heavier classified material and the discharge openin for the lighter classified material are located about the central vertical axis of the tank In, the discharge opening for heavier material being positioned at the bottom of the conical lower wall l2 and the discharge opening for lighte classified material being positioned in the upper portion of the tank in the cylindrical walled section and substantially on a level with the inlet conduit I 4.

The zoneof overflow from the tank Ill into the discharge funnel I5 is controlled by a collar I! which fits about the funnel i5 and is slidably mounted for vertica1 adjustment. The collar I1 is carried by cross members 18 secured to a screw threaded rod [9 which extends upwardly through the hollow shaft 20 and is supported by upper brace member 2! which is threaded at 22 for cooperation with the threaded rod ill to raise and lower the collar W by turning motion imparted to the hand wheel 23 which is fixed to the upper end of the rod H3. The brace 2| is fastened to the cross-frame member 24 which extends across the open top of the tanklil.

The hollow shaft 26 is journalled for rotation in the bearing 25 which is also mounted on the cross-frame member 24; and the shaft 20 carries on its lower end a plurality of impelle blades 26 which depend from the spider arms 21. The impeller blades 28 are positioned in the zone of overflow near the top of the tank l0. Rotary motion is imparted to the impeller blades 26 through pulley 28 which is secured to the hollow shaft 29 and is driven by any suitable source of power (not shown). The swirl of the rising current within the collar i1 is diminished and broken up by fins 29 attached to the outer periphery of the funnel I ii and extending outwardly to the collar .17. The fins 29 are spaced about the outer periphery of the funnel i5 and are shaped to have an inner surface to conform to the wall of the funnel and to have an upright outer surface to conform to the cylindrical wall of the colla ll. The fins 29 have an upstanding rectangular upper portion extending above the upper edge of the funnel l5, and a lower portion extending downwardly approximately to where the funnel is merges with the discharge tube l6.

Water or other diluent is introduced into the tank l0 through manifold 30 and tubes 3|, the

3 tubes 3| being connected to the manifold 30 and arranged to enter the tank In near the bottom of the cone shaped lower wall l2 near or slightly above where the axially extending discharge tube It turns outwardly from the tank.

In the operation of my apparatus, material to be classified is introduced into the tank In tangentially through the inlet conduit H at the liquid level in the tank. Rotary motion imparted to the impeller blades 26 causes these blades to sweep around in the tank to aid the tangentially introduced material to swirl around the cylindrical upper wall ll. As the material is thus swept around inside the tank in, the heavier material will slide down the walls of the tank to be discharged through the: discharge opening l3 which may be controlled by convem tional means (not shown). Water or other diluent in desired quantity is admitted to the tank in through tubes 31 and passes upwardly through the center of tank [0. The rising current along the central axis of tank It may pass into the lower end of collar ll and past the fins 29 which serve to break up swirling motion and cause the lighter material'passing upwardly between the collar l1 and the funnel [5 to overflow quietly into the funnel and pass out through the discharge tube Hi. The collar I1 is adjusted vertically by hand wheel 23 to select the zone of flow over the top of collar H and into funnel l5. As the heavier material gravitates to the bottom of the tank I!) and is discharged through the lower central opening 13, lighter material flows gently through the upper central outlet.

The heavier material is introduced and retained near the outer wall of my apparatus, and the lighter material is moved toward the center for discharge. The heavier material falls by gravity to the bottom and is washed by the diluent entering from the manifold 30, and the diluent and lighter material rises to the top and passes through the collar IT to the outlet funnel 15. or overflows the top of the collar 1'! as determined by the vertical adjustment of the collar [1. As the collar [1 is raised, more of the lighter material fioating on the surface is required to flow downwardly in the tank and is swept around by the rotating blades 26 before passing into the collar [1 and out of the tank through the funnel l5 and discharge tube It. Because the discharge tube It extends downwardly along the central axis of the tank, it ofiers only a minimum of resistance to the rota! tion of the material being classified.

It will be obvious to those skilled in the art that I have provided apparatus of great useful.- ness and high efficiency; and that, while one very practical embodiment has been shown and described, many modifications and changes can be made without departing from the scope of my invention as defined in the appended claims.

I claim:

1. In a centrifugal classifier, an open top tank having a cone shaped wall portion, means for introducing material substantially tangentially into said tank, a lower discharge opening for heavier classified material, an upper discharge opening for lighter classified material, both said discharge openings being positioned about the central vertical axis of said tank, and a tubular collar within said tank and surrounding said upper discharge opening and arranged for vertical adjustment with respect thereto, said collar extending above and below said upper discharge opening and being spaced therefrom so 4 as to form a flow channel between said collar and said upper discharge opening for the flow of said lighter classified material therethrough, said collar being open at both ends for the fiow of said lighter classified material into said channel and outwardly through said upper discharge opening.

2. In a centrifugal classifier, an open top tank having a cone shaped wall portion, means for introducing material tangentially into said tank, impeller blades arranged in said tank to impart rotary motion to material in said tank to be classified, a lower discharge opening for heavier classified material, an upper discharge opening for lighter classified material, both said discharge openings being positioned about the central vertical axis of said tank, and a tubular collar within said tank and surrounding said upper discharge opening and arranged for vertical adjustment with respect thereto, said collar extending above and below said upper discharge opening and being spaced therefrom so as to form a flow channel between said collar and said upper discharge. opening for the flow 01' said lighter classified material therethrough, said collar being open at both ends for the flow of said lighter classified material into said channel and outwardly through'said upper discharge opening.

3. Ina centrifugal classifier, an open top tank having a cylindrical upper wall portion and a cone shaped lower wall portion, means for introducing material tangentially into said tank. impeller blades arranged in the upper portion of said tank to. impart rotary motion to mate? rial in said tank to be classified, a lower discharge opening for heavier classified material at the bottom of said cone shaped lower wall portion, an upper discharge opening for lighter classified material, both said discharge openings being positioned about the central vertical axis of said tank, and a tubular collar with: in said tank and surrounding said upper discharge opening and arranged for vertical ad-.- justment with respect thereto, said collar ex-. tending above and below said upper discharge opening and being spaced therefrom so as to form a flow channel between said collar and said upper discharge opening for the flow of said lighter classified material therethrough, said collar being open at both ends for the flow of said lighter classified material into said chan, nel and outwardly through said upper discharge opening.

4. In a centrifugal classifier, an open top tank having a cylindrical upper wall portion and a cone shaped lower wall portion, means for introducing material tangentially into said tank, impeller blades arranged in the upper portion of said tank to impart rotary motion to material in said tank to be classified, a lower discharge opening for heavier classified material at the bottom of said cone shaped lower wall portion, an upper discharge opening for lighter classified material, said upper discharge openmg comprising a funnel shaped end on a discharge tube extending downwardly about the central vertical axis of said tank, and a tubu-Q. lar collar within said tank and surrounding said funnel shaped end and arranged for vertical adjustment with respect to said end, said collar extending above and below said upper discharge opening and being spaced therefrom so as to form a flow channel between said collar and said upper discharge opening for the flow of said lighter classified material therethrough, said c01 troducing material tangentially into said tank,-

impeller blades arranged in the upper portion of said tank to impart rotary motion to material in said tank to be classified, a lower discharge opening for heavier classified material at the bottom of said cone shaped lower wall portion, an upper discharge opening for lighter classified material, said upper discharge opening comprising a funnel shaped end on a discharge tube extending downwardly about the central vertical axis of said tank, a tubular collar Within said tank and surrounding said funnel shaped end and arranged for vertical adjustment with respect to said end, said collar extending above and below said upper discharge opening and being spaced therefrom so as to form a, flow channel between said collar and said upper discharge opening for the flow of said lighter classified material therethrough, said collar being open at both ends for the flow of said lighter classified material into said channel and outwardly through said upper discharge opening, and fins positioned within said channel to guide the fiow of material therethrough.

JOHN MARSHALL DAVIS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 872,555 Capps Dec. 3, 1907 1,825,157 Pardee Sept. 29, 1931 2,442,522 Wiegand June 1, 1948 2,473,488 Hughes June 14, 1949 

